1. Field of the Invention
The present invention relates to a dust-removing mechanism in an open-end spinning frame.
2. Description of the Prior Art
FIG. 1 of the accompanying drawings illustrates a conventional open-end spinning frame. A sliver A as it is introduced into a spinning unit 1 is advanced while being sandwiched between a feed roller 2 and a presser 3, and is separated into fibers by a combing roller 4 which rotates at a high speed that is surrounded by an outer wall 20 extending along the outer peripheral surface of the combing roller 4 with a predetermined clearance therebetween. The separated fibers are then transferred in the direction of the arrow along the circumferential surface of the combing roller 4 into a fiber feed channel 5. The fibers as they emerge from the fiber feed channel 5 are carried on a current of air and rotated at a high speed, and then are deposited on an inner peripheral surface of a rotor 6 in which a vacuum is developed. The fibers are thereafter pulled as a yarn out of a yarn delivery passage (not shown), and the yarn is wounded on a bobbin to form a yarn package.
The outer wall 20 has an opening 21 through which the circumferential surface of the combing roller 4 is partially exposed to a dust-removing chamber 7 disposed adjacent to the combing roller 4. Impurities and foreign matter B such as leaf pieces and neps, for example, in the sliver are discharged through the opening 21 into the dust-removing chamber 5 under centrifugal forces of the combing roller 4 as it separates the sliver. Other impurities and foreign matter B such for example as short fibers, waste cotton, and dust are separated from the surface of the combing roller 4 by an air stream produced by the rotation of the latter and then are discharged into the dust-removing chamber 7. The dust-removing chamber 7 has a small air inlet 7a in one end thereof, but is of a substantially closed construction. The other end of the dust-removing chamber 7 has an outlet 7b connected to a trash pipe 8 for delivering the impurities B. The trash pipe 8 is coupled to a side of a dust collector duct 9 which is shared by other spinning units. The dust collector duct 9 leads through an air blower 10 to a dust collector chamber (not shown). The impurities B separated and discharged into the dust-removing chamber 7 are discharged therefrom into the trash pipe 8 on a suction stream of air created by the action of the air blower 10, and then are collected through the dust collector duct 9 into the dust collector chamber.
The conventional dust-removing mechanism of the foregoing construction has suffered from the following shortcoming: As described above, the impurities B are carried on a current of air from the dust-removing chamber 7 into the trash pipe 8. Since it is necessary to develop a relatively strong suction air stream in the dust-removing chamber 7 for delivery of the impurities B, the dust-removing chamber 7 is of substantially closed construction. Therefore, a suction force due to the vacuum in the rotor 6 tends to be developed in the dust-removing chamber 7. This suction force is liable to cause the impurities B once separated from the fibers to be drawn back into the rotor 6 on a suction air stream generated by the latter, and to be deposited in the rotor 6. One solution to avoid such an undesirable phenomenon would be to increase the speed of air flow in the dust-removing chamber 7. However, such an air flow would peel not only the impurities but longer fibers off the surface of the combing roller 4, resulting in a poorer yarn yield. The outlet 7b of the dust-removing chamber 7 is constricted for increasing the speed of air flow and hence tends to get clogged with the impurities B passing therethrough.